Black-Footed Ferrets Detected Using UAVs Equipped with Thermal Cameras
Jesse T. Boulerice, Steller's Jay Solutions
January 8th, 2023
Steller's Jay Solutions, LLC
Fort Belknap Fish and Game Department
Idaho State University
World Wildlife Fund
Little Dog Wildlife
Recovery efforts for black-footed ferrets are challenged by a multitude of factors, one of which includes finding reliable techniques for detecting this elusive species on the landscape. Ferrets exhibit semi-fossorials behaviors and spend a significant amount of time in the underground burrow systems created by prairie dogs. Primarily nocturnal in nature, ferrets only come aboveground during infrequent and unpredictable bouts during nighttime hours. Currently, nighttime spotlight surveys are considered the best available method for monitoring ferrets (U.S. Fish and Wildlife Service 2016). However, this survey method requires biologists to spend many nights navigating around massive colonies of prairie dog burrows during which low detection rates and surveyor fatigue limit the effectiveness of surveys.
An important need in recovery efforts for the endangered black-footed ferret (ferret; Mustela nigripes) is to develop alternative techniques for optimizing the procedures used to assess the status of ferret populations at reintroduction sites throughout North America. Accordingly, the U.S. Fish and Wildlife Service Species Recovery Plan for ferrets currently lists a series of recovery actions directed at improving and evaluating new survey techniques for ferrets and prairie dogs (Recovery Actions 3.7.3.–3.7.5.; U.S. Fish and Wildlife Service 2013). Over the past decade, the technical uses for thermal cameras and Unmanned Aerial Vehicles (UAVs) have increased rapidly. The numerous utilities of these technologies have grown to include applications as a tool for effectively detecting and surveying a wide range of wildlife species. A series of pilot studies conducted from 2019–2021 on the Fort Belknap Indian Reservation provided first-of-its-kind evidence that handheld or truck-mounted thermal cameras could be used to detect ferrets (Boulerice and Hiller 2020, K. Bly, World Wildlife Fund, personal communication). Researchers suggested that combining thermal cameras with UAV technologies may be required to fully capitalize on the benefits of this potential tool for monitoring ferret populations. These results were among other promising studies that suggest thermal cameras could be used to detect cryptic and otherwise difficult-to-detect species and potentially achieve higher detection rates than compared to traditional survey methods (Focardi et al. 2001, Witt et al. 2020). Similarly, several studies have found UAVs equipped with thermal cameras to be capable of effectively surveying other small mammal species of similar body size, cryptic behaviors, and nocturnal activity patterns as ferrets (Bushaw et al. 2019, Karp 2020).
As part of a grant awarded to the Fort Belknap Indian Community by the Bureau of Indian Affairs Endangered Species Program, we conducted surveys for black-footed ferrets using UAVs equipped with thermal cameras at the Fort Belknap Indian Reservation. The goal of these surveys was to assess the effectiveness of using this method to detect and count ferrets during nighttime flights and develop a protocol for monitoring ferrets using UAV platforms.
During October 2022, we conducted 22 hours of UAV surveys for ferrets during nighttime flights and successfully detected 4 individuals. All ferrets observed by UAV were subsequently verified to species with on-the-ground spotlight surveys. However, in all cases, ferrets were easily identified in the live video feed of the thermal camera by prominent heat signatures against the cooler background landscape. The body shape, undulating movement patterns, and ferret-like behaviors (i.e., darting from prairie dog burrows) were clearly visible in these heat signatures. Additional wildlife species, including American badger (Taxidea taxus), American bison (Bison bison), coyote (Canis latrans), mice (Peromyscus spp.), and various unidentifiable bird species were detected during flights.
This effort marks the first time black-footed ferrets have been successfully detected using UAVs equipped with thermal cameras during nighttime flights. We consider this promising result to be a critical first step toward comprehensively evaluating how UAV-based survey methods might be incorporated into ferret monitoring and management efforts. Our results suggest that UAVs could be used to efficiently detect ferrets from the air, survey large areas at reduced survey times compared to traditional methods, and overcome other challenges (i.e., difficult terrain, limited road-access) associated with on-the-ground survey methods. Additional research to develop best methods for optimizing the value of UAV-based surveys for ferrets is anticipated in the near future.